An internal combustion engine (ICE) combusts fuel to produce driving force. The ICE typically includes a series of reciprocating pistons that drive a crankshaft. The pistons are slidably disposed within cylinders formed in a cylinder block. A cylinder head is secured to the cylinder block sealing the pistons within the cylinders.
The cylinder head is the detachable part of the top of the ICE that contains spark plugs, inlet valves, exhaust valves and may contain a camshaft. It seals the cylinder and forms the top of the combustion chamber. Generally, the cylinder head is an aluminum or iron casting that houses the combustion chambers, the intake and exhaust ports, and much or all of the valvetrain. The head (or heads, if an engine has more than one bank of cylinders) is always directly above the cylinders. An exhaust manifold is a network of passages that gathers exhaust gases from the various cylinder exhaust ports. The exhaust manifold is typically a separate component coupled to the cylinder head with threaded fasteners. The exhaust manifold routes the gases toward the catalysts and mufflers of the exhaust system. The cylinder head and cylinder block include a series of passages that facilitate coolant flow. Coolant is circulated through the passages to cool the cylinders, the area above the combustion chamber and the valvetrain components.
ICE manufacturers continuously strive to improve the overall operating efficiency of the ICE, as well as reducing costs associated with manufacture of the ICE. Traditional ICEs are more complex and inefficient than desired, making manufacture and assembly more difficult and more expensive.